A few things I've noticed so far compared to 40.41 and previous sets:
Improved driver properties inteface remains from 40.41
Hardware acceleration of OpenGL across multiple monitors actually works reasonably well now!
Reg hack to enable expanded AGP Settings tab in the driver properties opens up considerably more adjustments then were available before-unfortunately none of the options take effects, and it mis-detects current operating status of AGP transfer rate, and AGP Aperture size as well as AGP FastWrites and Sideband addressing.
If they can get it working it'll be a nice improvement-but for now the AGP Settings tab is completely non-functional anymore.
Options for Fast Linear MipMap Filtering in OpenGL have been removed.
That's an annoyance as enabling it caused an almost imperceptible image quality drop but improved performance.
DirectX anisotrophy now adjusted by slider, positive change IMHO
Texture Sharpening is enabled by default when FSAA is applied.
Allows DirectX OverRide of default Refresh Rate!
Definitely a very positive addition. Interestingly it does not allow for 800x600 adjustment though.